1. Field of the Invention
The invention relates generally to valve devices for controlling the flow of fluids and substances within the human body, and relates more specifically to such valve devices and methods for use in controlling urinary and bowel incontinence.
2. Description of Background Art
Urinary incontinence is a dysfunction of the bladder to securely retain urine until the. individual intends to void. Causes for urinary incontinence are many and affect all age groups, but tends to be more prevalent among females and the elderly. The major forms of incontinence are stress incontinence, psychogenic incontinence, and trauma, typically surgical, to the vesicle neck. Urinary incontinence is currently estimated to affect about 4% of the population, a figure that is growing due to population shifts toward longer life spans. At the present time, the direct and indirect costs related to urinary incontinence are estimated at between $1.8 and $10 billion per annum in the U.S.
Present methods for treating urinary incontinence are pharmacological, surgical, behavioral, and prosthetic implant devices. The least intrusive treatment that can achieve desired results always is recommended. However, each of the existing treatments have limitations and drawbacks. The behavioral treatment is useful in cases of minor dysfunction, while exercises can help minimize the effects in stress incontinence. The use of a prosthetic device has, historically, been less desirable as these devices can cause irritation to the sensitive sections of the urethra and ultimately necrosis should the prosthetic device result in circulatory insufficiency. In addition, application of the obturating collars of the older devices required that the urethra be severed and reattached, further complicating the surgical procedure and causing additional trauma to the tissue. Other forms of incontinence, such as bowel incontinence, require similar treatments.
There are several other environments in which fluid control within the human body is desirable. For example, impotence often is the failure of blood flow to the superficial and/or deep dorsal veins of the penis. Several penile implants are commercially available, all of which include some type of local trauma to the region. It would be a benefit to control fluid flow remotely and permanently with a reduced trauma to a localized region.
The leading penile implant on the market is available from AMS (Minnetonka, Minn.). That implant includes a pair of silicone cylinders that are surgically implanted in the penile corpus and attached to a pump placed in the scrotum. Erection is achieved by digitally locating the pump and manually pumping silicone fluid into a set of inflators. An internal "bleed-down" orifice allows the fluid to return to the reservoir at a controlled rate. This device is awkward to operate, places substantial amounts of hardware in physiologically and psychologically sensitive areas, and places unnecessary pressure on the tissues surrounding the inflators.
An alternative penile implant device includes a penile rod that simply is a plastic rod that is forcibly inserted by the individual into a surgically fabricated fold of skin along the side of the penis. Although functional, the device is capable of injuring delicate tissues if inserted incorrectly and has additional problems associated with maintaining the skin fold in a state of cleanliness.
At present, existing control mechanisms for human body fluids, such as blood, urine, and the like, are large and cumbersome, and cause significant trauma at the functional location. Such artificial control valves for bodily functions are a continuing source of problems for the medical industry. The tissue around the sphincters, or naturally occurring valves, are not designed to be deprived of blood flow or perfusion for long periods of time. This sensitivity to external constriction has caused most of the artificial devices to at least callous the area or render the tissue to a necrotic state.
One conventional inflatable cuff, also available from AMS, is designed for positioning about the urethra and has a binary control which allows the cuff to be fully inflated, then fully deflated at selected intervals. This artificial urethral sphincter is a silicone toroid that is positioned around the urethra. Applying the device involves severing the delicate urethra and threading the urethra through the hole in the device. The procedure is complicated by a restricted workspace and, in the case of females, the short length of the urethra. Upon inflation of the positioned device by an attached pressurizing device, the artificial cuff inflates and the interior surface of the toroid constricts the external surface of the urethra, collapsing the interior duct. Given that the average adult urinates only four times daily, the urethra is in a constricted state without blood flow for approximately six hours at a time. The combined effects of depriving the tissue of adequate perfusion for extended periods of time and being positioned in a sensitive area with an exposure to bacterial agents, results in poor long term viability for the urethra. The remedial action is to have the urologist surgically remove the necrotic area and reattach the urethra. Since there is a finite amount of urethra, the number of reattachments is limited.
Thus, there remains a need for an implantable control valve for selectively controlling fluid flow within the human body.